1. Field of the Invention
The present invention relates to the field of stimulating sandstone formations of oil and gas wells by use of an acid fracturing fluid containing a sulfonate ester.
2. Description of the Related Art
Acid fracturing is a well-stimulation operation in which acid is forced into formation at a pressure above the formation-fracturing pressure to cause the formation to crack open. The acid reacts with the fracture faces in a non-uniform pattern (etching) to form conductive channels that remain open without a propping agent after the fracture closes. While acid fracturing is usually applicable for carbonate formations, acid fracturing in sandstone formations is not a common practice due to the low rock solubility of mud acid.
For acid fracturing, it is desirable that the generated fractures remain open when the fracture pressure is released. When pumping acid with proppant at the same time, due to the tendency for the acid to react evenly with the fracture face and the fast reaction rate between the acid and the fracture face, there is a good chance that opposing fracturing faces match up when the fracturing pressure is released. The created disparities in flow paths through fast reaction between the acid and the fracture face could result in a narrower fracture width if the propping particles are embedded in the fracture faces that have been etched by the acid. When this occurs, the flow channels are narrowed, which results in reduced productivity.
A need exists for methods and compositions that are useful in effectively acid fracturing sandstone formations to enable efficient production of hydrocarbons from such sandstone formations.